500efi Saga Continues
 

So after replacing the entire valvetrain to get rid of lifter noise, upon removing engines this year for transom work; the rear exhaust valves are toasted. Heavily corroded looks like reversion. Engine has to come apart for the 3rd time. Anyone have issues with reversion on stock 500efi setup? Exhaust is cmi e top headers. They have been Pressure tested numerous times. No issues.

Before the rebuilds there was a lot of carbon build up but valves did not look like they look now. It's a stock cam, Johnson lifters, isky springs, scorpion 1.7 rockers, and trend push rods. Any help is appreciated. Thinking we may have to go dry to prevent this happening again. Going on 20k for top end rebuilds...should have left them alone.

Are you running mufflers ??

No

Switchable exhaust?
Picture of your exhaust angles and tips may help.

No switchabke exhaust. I'll take picture of tailpipe but there is nothing fancy about it. It's the standard cmi e-top. Termination of water into exhaust is 16-20" down pipe.

Check your tail pipes for cracks

I looked. Tails and headers are in mint condition. No rust, no corrosion, etc.

Cylinder #8
https://i.imgur.com/qS4uLE7.jpg

Cylinder #2
https://i.imgur.com/uhJB95q.jpg

I think it's reversion because both motors are identical in terms of pattern. Rear cylinders are bad. Front of engine appear good.

#8 is horrible. Yuk.

Rear cylinders primary tubes are the 'bottom' ones. Could be water leaks,,,,could be just the ignition timing. You pulled heads to get redone right ? Anything else touched other than removing heads, intake, dist, and exhaust ?

I didn't do the work...paid someone to do it. but I am only aware of heads, intake, exhaust, and dist coming off. Heads don't appear to be rotted.

Lower end was not touched

Setup
https://i.imgur.com/eKb7CeO.jpg

What is that mounted above your tailpipes, right on the transom?
[ATTACH=CONFIG]561285[/ATTACH]

It does look like like you have the Teague style switchable mufflers????

BTW the one air cleaner looks like its crushed and maybe choking that motor for air. It needs a new one.

When you did valve springs and lifters, did you service heads with valve job ? If yes; you have a issue else where.... If you only changed springs and lifters... you have a issue due to your seats and valves that continued leaking after changing those parts. Poor valve seal or leaking exhaust will cause reversion.

Look like solenoids to me, hard to tell

And make sure you don't have any exhaust leaks at the heads and also at the tailpipe connection. That will cause reversion too.

When you pressure tested the headers did you apply heat to the collector area and near the exhaust ports? I see a lot of headers that don't leak and as soon as you get heat in them, they begin to leak. People don't believe me until I show them.

It's corsa but not attached to anything and aren't operable.

I was told exhaust valves along with valve seals and valve job was performed. Spring pressure was increased but I doubt that would lead to reversion. Heads are going to machine shop Wednesday. The heads were decked not sure what else was done in terms of service.

I will take a picture of the heads. They are literally in mint condition. We did not apply heat when they were Pressure tested.

This was the valve post 300 hours. Looks like carbon but no rust like I have now...

https://i.imgur.com/niPYMZK.png

There is signs of water there. not much, its multi color and pitting. in my book that's some type of moisture

Are you sure the exhaust is good? things can change with heat. Like inner tube cracks. did you do a visual or pressure test?

Heads might be old enough where you're getting water that's starting to come through the exhaust port. I've seen that before on older heads. Something to check!

Had them Pressure tested 2 times in the last 3 years. Both times they checked out. Doesn't hurt to do them again

Dropped off heads yesterday with machine shop... his first guess was valve guides. He was right. See picture below. Not sure why this want checked during the first top end rebuild. Would have saved me a lot of time and money.

https://i.imgur.com/3rmvPBv.jpg

He is checking other things as well (i.e. Springs, valve job, valves, seals, etc).

Inspected headers. Everything looked good:

https://i.imgur.com/Rhps5ZW.jpg

https://i.imgur.com/r1u5T11.jpg

https://i.imgur.com/om7sYff.jpg

Moses so you for certain have the original cam? Just confirming and didn't catch thread til now. I've ran cams years ago with 5 deg less lsa and a ton of overlap with stock exhaust and have never issues like this. Late 80's learning era. Lol. I didnt idle around much then and when so it was always above 1,200 rpm. I feel bad for your situation and hope you get this resolved. I'm glad to see your valve guides are getting replaced but still gotta get to the root of the problem. This is going on with just the one engine correct? You owned the boat since new? I noticed the white flake over carbon look going on in a couple of the pictures which someone made note and does appear that moisture is heating up the carbon discoloring and flaking the carbon so to speak. Would be my best guess anyway.

But again you went 300 hrs without really many issues other than the what appears to be a moisture issue more so than what your getting now. Did you ck both sides of the head gasket as well as deck surface for any signs of water? I jumped in late here so sorry if I asked already addressed issues.

Yes pray for me!!! To answer some of your questions, yes it is a stock 500 EFI cam which from what I read is 114. Nothing crazy. And agreed based on the 300 hour picture I'd say there is minimal moisture. Nothing compared to what I have now.

Both engines are exhibiting the same issue. Rear cylinders are wet and laden with corrosion.

When pulling the head, I checked both gaskets for water cross porting. So no evedince of anything. I'll post a picture in a minute.

I showed some people my photos they tend to agree with the valve guide philosophy. Reversion tends to clean/steam the carbon out of the port area. As you can see all the carbon looks to be intact. They exhaust flakes do make me wonder a little now.

I just opened the pic of the guides. Ya not good. Surprised he got them out as easily as what he did. what year are these engines? For some reason I recall GM doing something funky with guides on certain year heads etc. Still doesn't appear that really any water is going beyond the corroded erea. No trail or path of least resistance you can see.

Picture of gasket...

https://i.imgur.com/KWzpvf7.jpg

Keep in mind you only see One side...the tips look bad on the right. Not sure if water made its way down there or lighting.

You'd just think there would be evidence of little water veins protruding beyond the corroded area of them.

the cast iron guides that were originally in the head have failed,using the bronze withe he salt water betw them and the cast iron is making a reaction,this will happen again.your best bet,,put cast iron sleeves back in.

losing compression all over the place.

17046 Correct head gasket? Also how much water pressure you runner and do you run pressure relief valves?

Also are you able to check block deck surface?

few questions:

1. Are the guides shown the original iron guides? Or replacement bronze?
2. Is it your opinion that the guides are causing the water corrosion on valves, or is it something else?
3. How can you tell compression is off? Gasket is mis-shaped?

This is the gasket that was used: Head gasket: felpro marine 17048

Not easily.